internal static bool Detect(Stream stream)
{
if (stream.Length < SuperBlock.Length + SuperblockOffsets[0])
{
return(false);
}
stream.Position = SuperblockOffsets[0];
byte[] superblockData = StreamUtilities.ReadExact(stream, SuperBlock.Length);
SuperBlock superblock = new SuperBlock();
superblock.ReadFrom(superblockData, 0);
return(superblock.Magic == SuperBlock.BtrfsMagic);
}
public VfsBtrfsFileSystem(Stream stream, BtrfsFileSystemOptions options)
: base(options)
{
Context = new Context(options)
{
RawStream = stream,
};
foreach (var offset in BtrfsFileSystem.SuperblockOffsets)
{
if (offset + SuperBlock.Length > stream.Length)
{
break;
}
stream.Position = offset;
var superblockData = StreamUtilities.ReadExact(stream, SuperBlock.Length);
var superblock = new SuperBlock();
superblock.ReadFrom(superblockData, 0);
if (superblock.Magic != SuperBlock.BtrfsMagic)
{
throw new IOException("Invalid Superblock Magic");
}
if (Context.SuperBlock == null)
{
Context.SuperBlock = superblock;
}
else if (Context.SuperBlock.Generation < superblock.Generation)
{
Context.SuperBlock = superblock;
}
Context.VerifyChecksum(superblock.Checksum, superblockData, 0x20, 0x1000 - 0x20);
}
if (Context.SuperBlock == null)
{
throw new IOException("No Superblock detected");
}
Context.ChunkTreeRoot = Context.ReadTree(Context.SuperBlock.ChunkRoot, Context.SuperBlock.ChunkRootLevel);
Context.RootTreeRoot = Context.ReadTree(Context.SuperBlock.Root, Context.SuperBlock.RootLevel);
var rootDir = (DirItem)Context.FindKey(Context.SuperBlock.RootDirObjectid, ItemType.DirItem);
RootItem fsTreeLocation;
if (!options.UseDefaultSubvolume)
{
fsTreeLocation = (RootItem)Context.FindKey(options.SubvolumeId, ItemType.RootItem);
}
else
{
fsTreeLocation = (RootItem)Context.FindKey(rootDir.ChildLocation.ObjectId, rootDir.ChildLocation.ItemType);
}
var rootDirObjectId = fsTreeLocation.RootDirId;
Context.FsTrees.Add(rootDir.ChildLocation.ObjectId, Context.ReadTree(fsTreeLocation.ByteNr, fsTreeLocation.Level));
var dirEntry = new DirEntry(rootDir.ChildLocation.ObjectId, rootDirObjectId);
RootDirectory = new Directory(dirEntry, Context);
}
